Major, Minor, Diminished and Augmented Triads

Triads are the foundation of the harmony of music.

If we look at the picture below, the top stave shows two sets of triads. The first triad is the G major triad and the second triad is the F major triad. The G major triad consists of the first note (root), the third note and the fifth note of the scale of G major, this is G, B and D. The F major triad consists of the root, third and fifth notes of the scale of F major, F, A and C. Another way of working out the major triad is through semitones. Between the root and the third is four semitones (G-G#-A-A#-B). Between the third and the fifth is three semitones (B-C-C#-D).  The F major triad between the root and the third (F-F#-G-G#-A) and between the third and the fifth (A-A#-B-C). The same system can be applied for all major triads.

If the triads in the picture below were minor, the G minor triad would consist of the first note, third note and fifth note of the scale with a lowered third, the 3rd note would be lowered a semitone (G, Bb, D) and F minor (F, Ab, C). There are three semitones from the root to the third in G minor (G-G#-A-A#(Bb)), F minor (F-F#-G-G#(Ab)) and four semitones from the third to the fifth in G minor (A#(Bb)-B-C-C#-D), F minor (G#(Ab)-A-A#(Bb)-B-C). All minor triads can be worked out in the same way.

The diminished triad has a lowered 3rd and 5th, the 3rd and 5th note would be lowered a semitone. If in the picture below were diminished triads, the G diminished triad would consist of G, Bb, Db and the F diminished would be F, Ab, Cb. The distance between the root and the third is three semitones and between the third and the fifth is also three semitones.

The augmented chord has a raised 5th, the 5th note would be raised a semitone. It has four semitones between the root and third and also four semitones between the third and the fifth. The G augmented triad would consist of notes G, B, D# and the F augmented would consist of notes F, A, C#.

Note:
Three semitones is a minor 3rd, four semitones is a major 3rd.
A#(Bb), G#(Ab) are examples of enharmonic equivalents. The note sounds the same but has a different name.

Major triad: major 3rd and minor 3rd
Minor triad: minor 3rd and major 3rd
Diminished triad: minor 3rd and minor 3rd
Augmented triad: major 3rd and major 3rd


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Baxter, Harry and Michael Baxter. The Right Way To Read Music. Tadworth: Right Way, 1993. Print, pp. 64 and 65.